1. Field of the Invention
The present invention is related to a communication device for sending and receiving data.
2. Description of the Background Art
FIG. 10 is an explanatory diagram showing a data processing system with a conventional network interface card (hereinafter referred to as NIC). As shown in FIG. 10, an NIC 10 consists of a bus interface 1, a local memory 3 and an ATM adaptation layer LSI 4 (hereinafter referred to as AALLSI).
The AALLSI 4 receives data from outside and, after processing the data, writes the processed data into a data receiving buffer area 31 in the local memory 3 via a local bus 101. The bus interface 1 transfers the data, which is stored in the data receiving buffer area 31 in the local memory 3 via the local bus 101, to a host memory 2 via a host bus 100 by means of a DMA transfer.
In the above-mentioned NIC 10, when data is received, each data transfer between the local memory 3 and the AALLSI 4 or the bus interface 1, respectively, must be performed via the local bus 101. In short, access to the local bus 101 is required twice, which causes deterioration in latency and throughput in data transfer processing.